Tag Archives: philosophy

Poor Apologetics 7: You Can’t Trust Your Brain

The Theist’s Argument: You Can’t Trust Your Brain if Evolution is True

You can’t trust anything your brain tells you unless your brain was created by God. If a God designed your brain to make correct logical deductions, then it is reasonable to trust it. Whereas atheists have no reason to believe in science, trust their own thoughts, or believe any conclusion they reach is reliable because natural selection doesn’t need your thoughts and beliefs o be true or grounded in logic, it only needs your brain to work well enough to keep you alive long enough to pass on your genes.

Why They Use This Argument: (What they believe):

In episode 269 of Dogma Debate,  Texas preacher, Eric Hernandez argues, in what he calls the “Evolutionary Argument Against Naturalism,” that:

If there is no God, then the only explanation of our existence would be naturalistic evolution… it’s aim is for survival value and not truth value… which means my beliefs, if there is no God, do not have to be true… they just have to cause survival value in my behavior…

If atheism’s true, your beliefs don’t have to be true, they just have to work in the sense that they grant survival value. And if that’s the case, then the atheist now has a defeater that takes away any justification for any belief that his brain will produce.

If you are scratching your head, you’re not alone. David Smalley was just as confused. Later in the episode, Eric attempted to explain what he meant by giving two examples.

In his first example, he explains what he means by having “a defeater.” Eric describes a person who woke up in the middle of the day and formed a belief that it was 12:00 because that was the time he saw on his microwave clock. However, the clock was flashing, there was water under the fridge, and it was hot in the house, so the person came to the conclusion that the power must have gone out.

If your belief is formed on the basis of what the microwave says, then you now have a defeater for the belief that it’s 12:00… you are no longer justified on the basis of the microwave that it’s 12:00, even if it is.

In his second example, Eric describes two people who each see a car coming toward them and move out of the way, thereby surviving to propagate the species. The first person moved because he believed the car could injure or kill him if he were hit. The second man moved because believed he was Superman and he needed to continue to appear human.

The true and false beliefs both produced equivalent survival value in this situation because both people avoided being hit by the car.

If you’re an atheist you now have a defeater for everything you believe, because you have no way of verifying what you believe if your beliefs are only aimed at survival, not truth.

In his debate with Matt Dillahunty, Matt Slick made a similar argument.

You see, if our physical brains are limited to operating under the laws of physics and chemistry, then we need to ask how such a physical mechanism produces proper logical inference. In other words, how does one chemical state in the brain that leads to another chemical state in the brain produce proper logical inference?

… This is a serious problem in secular humanism. It means that in this naturalistic perspective you cannot trust your brain to produce proper logical inference because it’s just reacting chemically.

The Rebuttal: (Why the argument doesn’t work.)

This argument is flawed on many levels. Firstly, the fact that thousands of religions are practiced around the world proves that even if a God exists, the majority of humans are still capable of having false beliefs and thinking they are true.

Secondly, our brains make mistakes, we know that. This isn’t a surprise. For the most part, Christians and atheists both freely admit that we are imperfect and our minds are faulty. Our memories are flawed. We are bad at predicting odds. We all have biases that affect our perceptions. We, at times, come to erroneous conclusions.  This is true whether a god exists or not.

Thirdly, beliefs that align with reality have a higher survival value than beliefs that don’t. This means that while we acknowledge our brains are imperfect, we have good reason to trust that our perceptions and deductions about the world around us are fairly accurate.

To prove my point, let’s go back to Eric’s example of the two people who avoided getting hit by the car. Both people were able to:

  • identify that a car was approaching.
  • predict the trajectory of the car.
  • recognize that a large energy transfer would take place if the car hit them.
  • acknowledge that the energy transfer would be harmful or fatal to humans.
  • locate a safe place where they could go to reduce their risk of being hit by the car.

I could continue listing beliefs held by both, but you get the point. I would challenge Eric to provide an example of a false belief that gives higher survival value which is not simultaneously dominated by true beliefs.

In Eric’s example, both of the men had far more true beliefs than false ones. The only place where the two disagreed was when one of them held the additional belief that he was Superman.

The belief that he was Superman allowed the second man to avoid being killed by the car, but that belief could actually provide negative survival value if the man were to make other decisions based on that same assumption. For example, if he were to put on tights and try to fly off a building or demonstrate how bullet-proof his skin is.

Beliefs don’t live in a vacuum. Beliefs affect actions and influence other beliefs. Even if only 1 in 100 people with the false Superman belief did anything other than avoiding oncoming cars, they would not be as likely to pass on their genes as the people who don’t think they are bullet-proof and can fly.

Eric and Matt are right when they say we can’t trust our brains explicitly. While our brains are very effective tools, they are not infallible. The scientific method was designed to eliminate or control for the problems we are aware of. There may be other issues which we haven’t found, but when we do we will alter our testing criteria accordingly.

Atheists don’t claim to have absolute knowledge on the subject, and in reality, the kind fo absolute knowledge Christians demand would be impossible even for their God. In his book, Sense and Goodness Without God: A Defense of Metaphysical Naturalism, Richard Carrier explains why:

Even a God could never have certain knowledge, because he could be in error about his being infallible. Consider what philosophers call a “Cartesian Demon.” Suppose some demon were actually solely responsible for sending you all your experiences, whatever they were, and this demon made sure you never knew the real cause. You could even be fooled into thinking you were an all-powerful, all-knowing Creator God, and you would never be the wiser. It follows that if there is a god, he could well be the victim of such a Cartesian Demon. He could never be certain that he wasn’t. It is therefore irrational to demand certainty for any of our knowledge. Not even a god could have that!